1. The Field of the Invention
The invention relates to a method and a device for transferring workpieces.
2. Background and Relevant Art
A process for manufacturing metallic products may comprise one or more shaping processes and additional machining processes for a workpiece. Often during a shaping process, not only is the desired product shape obtained, but the workpiece may also include other areas necessary for the shaping process or that result therefrom which must be subsequently removed from the actual product. For the particular processes, the workpiece must then be transferred from one shaping machine to another shaping machine or another processing machine. The problem on which the invention is based is explained below, using the example of a shaping process using drop-forging, which however does not limit the invention thereto.
In drop-forging, the workpiece is brought into the desired shape using a shaping machine having precisely operated hollow mold tools. During shaping of the workpiece blank in the hollow mold tool, excess material is outwardly displaced from the mold, and a projection or peripheral burr may form on the forged workpiece, which is then removed from the actual product in further processing. For this reason the drop-forging is usually followed by a deburring device to remove the peripheral burr.
During the shaping process for the forging and deburring, the workpieces to be processed must be transferred from a forging device to at least one deburring device. For automated handling of the workpieces, handling devices such as manipulators and industrial robots are known which have grippers for grasping and temporarily holding the workpieces, and which insert the workpieces into or remove them from the shaping machine. Manipulators are manually controlled movement devices generally having particular process-specific controls or programs. Industrial robots are universally applicable automated movement devices having a sufficient number of degrees of freedom of motion and a freely programmable control.
An automated unit for drop-forging and deburring of metal parts is known from DE 31 48 652 A1. This reference discloses, for example a vertical press and a deburring press operated by two robot pairs, the one pair being provided with individual horizontal arms and the other pair provided with two horizontal arms opposing one another at an angle of 180°, and each having end pincers. The robot pair having the two opposing arms is able to rotate by 180°, and is provided for placing the metal on the solid die part after it exits the oven and/or for removing the lifted drop-forged piece and placing it between the plates of the deburring machine. The workpiece is moved from the drop-forge to the deburring machine by gripping the workpiece at the peripheral burr produced during forging, and moving the robot in the direction of the deburring machine while the arm rotates by 180°. The other robot pair is provided for moving the workpiece during the forging process.
This device has a very complicated design because separate robot pairs are provided in each case for loading the machines and for the forging process. In addition, due to the need for accessibility by the robotic arms which are rotatable by 180°, the possibilities for configuring the machines in the unit are limited.
The device known from DE 203 11 306 U1 for shaping a workpiece by automatic handling comprises at least one shaping machine having at least two tools which are movable relative to one another for shaping a tool in a predetermined (or predeterminable) shaping position during at least one shaping step, and at least two handling devices for securely holding the workpiece in the shaping position during the shaping step—and thus also when the tool(s) strike(s) the workpiece. In addition to holding the workpiece during shaping, the handling devices may also perform other handling operations such as shifting the workpiece from one working region of a shaping machine to a next working region, or from one gravure of a tool to a next gravure, or from one shaping position to a next shaping position, rotating or swiveling the workpiece, in particular for changing a shaping position, picking up the workpiece from a pickup device, or conveying the workpiece to or from the shaping machine, in particular to a deposit station.
By use of the device described in DE 203 11 306 U1, a workpiece can be securely held and conveyed by only one handling device. If the shaping process is followed by an additional machining process, such as deburring of the workpiece, in practice, the workpiece is deposited on a deposit station, such as a swivel arm, by the handling device responsible for the shaping process. The swivel arm then moves into a transfer position for an additional handling device for the additional machining process, and the workpiece is taken from the deposit station in this transfer position and positioned in the appropriate machine. However, transferring the workpiece by means of a swiveling deposit station can be complicated, and also relatively time-consuming.